Cement is commonly used as the main material to produce concrete, however, the process of
production of cement is causing environmental problems. The amount of CO2 emission from cement
industries due to the calcinations of limestone and combustion of fossil fuel is in the order of
approximately one ton for every ton of cement produced. To produce environmentally friendly
concrete called geopolymer, it was proposed that a new material could be produced by a
polymerization reaction of alkali liquids with Si and Al as source materials of geological origin
materials. Si and Al are derived from pozzolanic materials or aluminosilicate mineral powders, for
example, powders of metakaolin or by-product of industrial and agricultural materials such as
lignite ash and agricultural ashes. This research was conducted to study geopolymers made partly
from < 45 μm powders of fly ash, bagasse ash and rice husk ash. Sodium hydroxide concentration of
10 molar (10MNaOH) and sodium silicate (Na2SiO3) solutions were used as alkali activators by the
mass ratio of Na2SiO3:NaOH at 3:2. The geopolymer specimens were cured at room atmosphere
for 7, 14, 21 and 91 days for characterization. SEM/EDS, XRF and UTM were carried out for
microstructures, chemical compositions and compressive strength, respectively. Finally, the cost
of production of specimens from cement and geopolymers were compared because of the the carbon
tax concern
Keywords: Geopolymer,